From Aug 2006 - Nov 2013 WeDig provided a live forum for diggers & fans of Vindolanda. It has now been mothballed and will be maintained as a live archive.

Here you will find preserved 7 years of conversation, photos, & knowledge about a site many people love. Vindolanda gets under the skin. (Figuratively and literally as a volunteer excavator!) It's a place you remember, filled with people you remember!

Thanks for 7 great years!

STRATEGIC OVERVIEW

The sheer scale and impressiveness of Hadrian’s Wall and its attendant fortifications, even in a ruinous state, often lead visitors to conclude that these structures were meant to provide a defensive fighting platform, in much the way that medieval castles were used by their own garrisons. Perhaps surprisingly, neither the Wall nor the local forts were intended for such use.

‘Grand strategy’ may imply a coherent, objective, long-term analysis of economy, military need, political considerations and the changing nature of the potential enemy threat. It must be emphasized that Roman ‘grand strategy’ is more a reaction to changing conditions than an attempt to influence those conditions ‘proactively’. One will not find a ‘general staff’, ‘war colleges’, or ‘institutes’ devoted to studying Roman strategic issues. Most importantly, the Roman perception of the world, one which remained remarkably consistent over centuries of time, was that the most efficacious approach was one of deterrence. The army’s small size combined with the Empire’s enormous frontiers made deterrence—the knowledge that an attack on Rome would result in massive retaliation, up to the outright obliteration of one’s people—a crucial yet intangible part of the Roman defense. The forts, walls, ditches, and fortresses are certainly impressive; but perhaps more important than these is the fear and respect Rome sought to instill in its potential adversaries.
This summary will briefly and very broadly discuss Rome’s responses to the changing nature of her relations with non-Romans on her frontiers. Imperial grand strategy may be divided into four broad periods:

Mobile Defense (middle 4th c.-476 CE) From Constantine to the end of the Western Empire.

It is easier to understand the psychology underpinning Roman grand strategy if one realizes that our understanding of a ‘frontier’—a fixed boundary, agreed upon between different jurisdictions, each of which possesses sole authority in its own territory (think of ‘passports’)—was quite different from that of the Roman era (or in fact of most periods prior to the modern age). Such a conception is based upon settled agreement over time between two parties concerning the location and meaning of their mutual ‘frontier’.

Contrast this with what I’ll call an ‘evolving’ frontier, such as the 19th century American West. In this case, the frontier was defined as a zone of ongoing military activity and greater or lesser civil administration, which acted as a buffer between ‘settled’ areas and ‘uncontrolled’ regions. Moreover, this frontier tended to move westward, such that purely military zones became increasingly peaceful, and eventually entirely civilian in nature.

The Imperial boundaries were not nearly as neatly delineated as a modern map of the Empire might lead one to think. While some eight legions were concentrated in first century Upper and Lower Germanyroughly, modern Holland and Germany to the west of the Rhine , for example, the river itself was not considered to be a ‘defensive barrier against large-scale invasion’. Roman patrols, indeed large scale Imperial incursions, were routinely carried out east of the Rhine, and there is strong evidence that the military maintained a substantial presence east of the river. Rather, the Rhine, and other linear boundaries, acted as a hindrance to incursions (rather than an absolute barrier). If raiders did cross the river (problematic in any case), they would simply find themselves in an area of little value, facing several legions, and unable easily to retreat if brought to battle. In short, the local real estate provided a convenient location in which Roman forces could destroy any incursions long before they could pose a threat to more important regions. Moreover, Roman policy in this period did not envisage a permanent defensive posture, and indeed additional conquests tended to leave former ‘borderlands’ deeper within the Empire. This provided a sound reason not to expend labor and money on static defenses.

Britain itself provides an example of this dynamic. The period 43-122 sees a steady expansion of Roman control. The pattern of conquest and pacification follows roughly thus for any given region:

Military resistance defeated;
Garrisons established to control area;
Growth of civil presence;
Increasing Romanization and growth of regional economy;
Decreasing military presence as frontiers move away.

Therefore, fortifications were constructed in order to suppress local disorder rather than to protect against ‘outside aggression’. As Roman conquest moved north, such districts tended to become more Romanized., and new ‘buffer areas’ (as in southern Scotland in the last quarter of the first century) protected the steadily more peaceful areas to the south.

Though Hadrian and his successor reoriented Imperial policy for several reasons, not least among them was the fact that ‘frontier’ zones had by the early second century become themselves quite Romanized, complete with a strong local/region economy spurred by the building of coloniae and the presence of a large ready-made consumer market in the form of the large frontier garrisons. This meant, in effect, that the ‘important regions’ which the army was tasked to protect now included the frontier areas themselves. The requirement, then, was to protect areas which lay close to potential threats but which were now increasingly integrated into the Imperial economy.

Hadrian possessed two alternatives: first, he could engage in the traditional Roman strategy of further conquest (moving the frontier zone away from valuable districts once more), or he could change the Empire’s stance from one of expansion to one of consolidation. He chose the latter course, not least because the Empire had reached, in Britain, Germany, and the East, its natural limits beyond which there was no economic gain to be made. In the East, of course, the Empire faced another large-scale power, Parthiaroughly, modern Syria, Iraq, and parts of Iran, which made attempts at permanent conquest and Romanization difficult at best.

The second alternative provided a means to protect the frontier districts, but required an abandonment of an ‘offense-oriented’ policy on the large scale. In this scheme, the Army would adopt a strategic defense, protecting the Empire as it stood, while remaining in an operational offensive stance. The legions and auxiliaries would remain fully prepared to repel large-scale incursions—indeed, to anticipate developing threats by expeditions into hostile territory, there to engage the enemy before he could invade Roman possessions. This left to be dealt with the far more common lesser threat of ‘low-level incursion’, ranging from ‘cattle-rustling’ to small groups prepared to raid farms or undefended villages.

Roman military doctrine envisaged a series of frontier fortifications which would act as an absolute deterrent to the smallest threats, while against larger potential incursions they would provide both advance warning to the legions and possibly some hindrance as well, giving the ‘heavy brigades’ time to deploy (and optimally, to meet the enemy well beyond the frontier).

The Army’s mission was redefined such that it would anticipate and meet more serious threats well beyond the frontier, engaging in the sort of open-field battles at which it was so adept, while lower level threats to local security would be dealt with by defenses whose purpose was not so much to provide a ‘fighting platform’ as to deter/warn of/delay such incursions. Hadrian’s Wall was but one of a series of frontier defenses built in this period in support of the linear defense strategy.

Hadrian thus abandoned his predecessors’ expansionist policy in favor of consolidation; frontiers would henceforth act as formidable barriers to smaller, opportunistic incursions (eg, ‘cattle rustling’, small bands of barbarians, and the like) while the existing garrisons would continue to train for offensive activity—but with the intent of pre-empting threats to the Empire, beyond the frontiers if possible, rather than with any idea of further conquest.

The system worked very well so long as the Empire was able to economically, militarily and psychologically dominate potential opposition. Along the Rhine and Danube, and on the Dacian frontiers, Imperial policy worked, as ever, to establish and maintain friendly client states among the ever-shifting power structures among the barbarians. Judicious use of gold, flattery, and of course the implied threat of military coercion in the form of the legions, sufficed to prevent any large-scale threats for much of the second century. The one danger, of course, lay in the possibility of a larger barbarian confederation arising, or a more organized, aggressive state than Parthia, both of which might conceivably not be so easily deterred by gold, gifts or military power.

The first such threat materialized in the mid second century, forcing Marcus Aurelius to wage a protracted campaign against the Marcommani and Quaditwo of the larger German tribes along the upper Danube. While several prior raids by other tribes were effectively contained by the Hadrianic system, this larger confederation proved to be far more dangerous—and since Aurelius was waging a war against Parthia, the frontier forces were incapable of containing the Germans. At the same time, non-German tribes opportunistically crossed the Danube further east. Germans in the West managed to invade Italy itself, while various other tribal groupings penetrated into the Balkans. Though the situation was eventually stabilized by Aurelius, the ‘local’ forces of the linear defense system, no matter how well-trained, were not capable of defeating a threat on this scale on their own—and once the enemy had passed through the frontier districts, the interior—peaceful for generations—was defenceless.

The next century saw the beginnings of a centralized field force: initially composed of legionary detachments and auxiliary cohorts gathered from across the Empire, which usually never returned to their parent units, a central army grew around the emperor himself, accompanying him on the incessant campaigns which characterized the third century. This force proved its worth in battle and its units were informally identified as ‘companions’ to the emperor.

Diocletianemperor 284 CE-305 CE attempted to restore a system of linear defense by greatly strengthening the frontiers, creating heavily fortified zones extending as much as 100 miles behind the frontier line itself, in an attempt to provide a secure base from which local forces could contain, then attack and defeat many incursions. The central field forces were available to assist in dealing with larger threats. This ‘defense in depth’ rendered Roman supply bases and settlements secure from anything less than a formal siege, provided refuges for Roman forces in the event of a reverse and were generally very successful in preventing a repeat of the large-scale incursions of the third century.

Diocletian’s successors continued to build the central forces, but by taking the best of the frontier forces; this weakened the ‘defense in depth’, effectively reducing the frontier forces’ ability to actively contain enemy threats and substituting a ‘mobile defense’—relying upon central forces to arrive at a crisis point. Over time, the Germans were once again able to penetrate the frontier defenses, and once past them, could roam at will (as in Gaul in the mid 4th century, and during the Adrianople campaign of 377-8) until the central armies could deploy. Worse, should any serious reverse befall the central ‘elite’ forces, there was now no pool of highly trained men along the frontiers from which losses might be made good. This, among other factors., foreshadowed the ultimate collapse of the Western frontiers in the early fifth century.

When the frontiers, due to lack of effective manpower and support, were finally and permanently breached during the early fifth century, the central armies continued to exist, accompanying emperors and would-be emperors in an increasingly futile attempt to retake lost territories. Unfortunately, once a province was lost, so was its tax base and manpower—and so each successive reverse meant that the army was left with fewer resources to rectify the situation. The Empire, especially in the West, resorted increasingly to wholesale incorporation of barbarian warbands and their families as foederati—fighting under their own leaders in their own style. Such groupings, essentially consisting of entire tribes, formed the basis for the successor states of the fifth century.